Antenna mounting structure



Dec. 6, 1960 L. H. FINNEBURGH, JR

ANTENNA MOUNTING STRUCTURE Filed NOV. 14, 1958 FIG. 2

IN V EN TOR.

LEWIS H. FINNEBU GH JR.

V i f f% me W ATTORNEYS thereon.

ANTENNA MOUNTING STRUGTURE Lewis n. Finneburgh, Jr., 221889 Shelburne Road, S ake Heig t Ohio EiledNov. 14, 1958, Ser. No. 774,007 4 C a ms- (c 18 -3 This invention relates to radio and television antennas and the like involving an elongated boom adapted to be mounted horizontaly on a vertical mast. The invention relates more particularly to antenna mounting structures for holding antenna booms rigidly to their masts and preventing both sagging of the booms and tipping of the booms in either direction from their desired horizontal ll l In recent years there heas been a marked trend in the design of antennas, particularly television and FM radio antennas, to employ very long horizontal booms having a considerable number of driven and parasitic antenna elementsmounted at intervals along the boom to extend transversely thereof. This makes the assembly of the boom and antenna elements not only quite long, but also quite heavy, so as to require fairly sturdy bracing to prevent the boom from sagging and from tipping in either direction under wind and ice loads.

It has heretofore been common practice to secure the boom to the mast close to the upper end of the mast, using a conventional saddle and U-bolt bracket for the purpose. To brace the boom against sagging or tip ping, a pair of oppositely extending, diagonal, compression braces has often been employed, the lower adjacent ends of the braces being secured to the mast for vertical adjustment thereon by means of another saddle and Ll-holt type of bracket, and the upper ends of the braces being pivotally secured to points on the boom spaced outwardly on opposite sides of the mast. Tightening of the latter bracket on the mast thus provides a rigid triangular structure. However, the braces must be made of material having a substantial cross section if they are to have sufllcient rigidity to resist longitudinal compression loading. Also, the assembly is heavy and cumbers lonie, to handle, as well as to ship, and is not as easily quickly installed as desired by commercial antenna installers.

The principal objects of the present invention are to provide improved antenna mounting structures for securing a boom to a mast more expeditiously, while still providing rigid bracing of the boom against sagging and tipping; to, reduce the Weight and cost of the antenna mounting structures; and to provide improved structures of the "character described which are collapsible for packaging in a carton of minimum dimensions which will accommodate the boom and antenna elements mounted Theforegoing objectives may be accomplished, in part, simply by using diagonal braces extending above the boom, instead of below the boom, the braces being designed to carry only tension loads, rather than compresloads. This permits the braces to be made of inexpensive, small diameter, resilient metal rod or wire, such as tempered aluminum rod. In accordance with the invention, the securing of the diagonal braces to the mast issimplified, both as to structure and installation, by merely hooking the upper ends of the braces over the iippe redge of the hollow tubular mast commonly em-' 2,963,l2 Patented Dese, 19. 0

Playe to supp rt radio n t l i n anten asy means of a properly shaped hook structure, as hereinafter more fully described, this mode of attachment of the diagonal braces to the mast may be made secure and reliable without requiring the placement and tightening of any bolts and nuts and while wholly eliminating the second saddle and U-bolt bracket heretofore commonly vention is not intended to be limited to its use for mounting radio and television antennas as shown and described herein for illustrative purposes.

The objects, features, and advantages of the invention will be more fully understood and appreciated from the following more detailed description of a specific example thereof, and from the accompanying drawings in which:

Figure 1 is a fragmentary, elevational view of a television antenna mounted on a mast in accordance with the invention;

Fig. 2 is a vertical sectional View, taken as indicated by the line 2,2 of Fig. l, to show how a diagonal brace may be pivotally secured to the antenna boom of Fig. 1

Fig. 3 is a fragmentary, elevational view, on an enlarged scale, showing how the diagonal braces of the antenna of Fig. 1 may be hooked over the upper edge of the hollow mast, a part of the mast being shown broken away for clarity;

Fig. 4 is an enlarged, fragmentary, elevational view showing the hook formed on the upper end of one of the diagonal braces in the structure of Fig. 1;

Fig. 5 is a further enlarged, fragmentary, elevational view of the structure of Fig. 3, showing how the free end of the hook formed on each diagonal brace can bite into the interior surface of the mast for securely holding the hook in place thereon.

Referring first to Fig. 1 of the drawing, a hollow, cylindrical, tubular mast 10 may have a boom 11 secured thereto in a conventional manner by a suitable saddle 12 and U-bolt and nuts 13. The saddle and U-bolt construction may be any of the types conventional in the art and, therefore, is not shown in detail; The

boom 11 is preferably a hollow tubular member and may be either round, square, or rectangular in cross section, aboorn that is square in cross section being shown in this instance (Fig. 2)..

The boom 11 may have a large number of driven and non-driven or parasitic antenna elements mounted elements 14 and 15 is shown mounted on respective in- .sulators 16 and 17 (transmission line connections to the antenna elements being omitted for simplicity). Additional driven or non-driven antenna elements. (not shown) would be mounted in a generally similar manner, with or Without insulators, at points spaced further along the boom in. both directions from the mast 1t Tipping and sagging of the boom 11 is restrained by a pair of diagonal braces 21 and 22. These braces may suitably be formed from relatively small diameter, solid wire or rod, preferably made of aluminum forminimum weight and tempered to have a relatively highdegree of resiliency. The lower outer end of each brace 2 1and, 22 may have a simple loop or eye 23 formed thereon so that the braces may be pivotally secured to the boom 11 by means of bolts 24, washers 25, and nuts 26 (Fig. 2), or by rivets or the like if desired.

The upper end of each brace 21 and 22 is bent to form a hook structure adapted to be forced downwardly into the open upper end of the mast 10, as shown in Fig. 3. The hook structure on each brace may suitably comprise a downwardly directed leg 30 having a bend at its lower end to provide an upwardly and laterally extending diagonal end portion 31, which may originally make an angle x with the downwardly extending portion 30, the original angle x preferably being substantially less than 90 (Fig. 4).

The horizontal extent of the upwardly and laterally extending diagonal end portion 31 is designated on the drawing by the dimension z, this dimension preferably being selected to be slightly greater than the inside diameter of the largest mast commonly employed for mounting relatively heavy antenna structures of the type with which this invention is concerned. When the hook structure described is forced downwardly inside the mast, the angle x is decreased by bending the hook structure at the bend 32 thereof, as represented by the smaller angle y shown in Fig. 3, so that the horizontal distance z is proportionately reduced to a dimension no greater than the inside diameter of the mast. When applied to masts of smaller inside diameter, the angle x and dimension z will simply be further reduced by forcing the hook structure into the upper end of the mast. The resilient bending of the hook structure at the bend 32 causes the free end of the hook structure at the point 33 thereon to bear tightly against the inner surface of the mast and to bite into the soft aluminum, of which the masts are normally made, sufficiently to prevent upward sliding of this free end of the hook portion if the tension force on the brace should reach a value that might otherwise tend to straighten out the thin rod material at the bend 34 therein and pull the hook structure out of the top of the mast.

As mentioned above, one of the advantages of the particular brace construction to which the invention is directed is that the braces permit packaging the antenna in a carton of minimum dimensions which will accommodate the boom and antenna elements mounted thereon. As shown in Fig. 1, downward swinging of the braces 21 and 22 into parallelism with the boom 11 might normally be prevented by the antenna elements 14 and 15, except for the fact that the braces are of resiliently flexible wire or rod so that they may be resiliently bent as indicated in phantom outline in Fig. 1. The braces may be held in their bent positions by the carton in which the antenna is packaged. Being resilient, this bending may be accommodated by the braces without taking a permanent set. Thus they will straighten out when the antenna is removed from the carton.

An obvious and equivalent variation of the specific structure described is one in which the hook structures of the tension braces 21 and 22 are made of a fairly stiffiy resilient wire or rod, as shown and described, but the remainder of these braces is made of a flexible cable, chain, braided or lightweight wire, or the like having little or no resistance to bending but substantial strength in tension. As will be apparent, the flexibility of the body of the braces will provide the equivalent of a pivotal connection to the boom 11, whereby the bolt 24 and nut 26, or other suitable connection of the braces to the boom, may be as tight or rigid as desired without altering the character of the mounting structure in any material respect, either as regards its foldability for packing or its operation when mounted on a mast.

It will be apparent from the foregoing description of an illustrative embodiment of the invention that the antenna may be simply and quickly mounted on a mast by first slipping over the top of the mast the single U-bolt and saddle assembly carried by the boom and then hooking the two braces over the upper edge Of the mast, The

mounting operation is completed by merely adjusting the height of the center of the boom on the mast so that the braces 21 and 22 carry a tension load imposed by the boom and the boom is substantially straight, and finally tightening the nuts associated with the single U-bolt to fix the height of the center of the boom on the mast. Braces of the type shown and described are capable of withstanding high tension stresses without the hook structures on the upper ends thereof being distorted and pulled out of the upper end of the mast. Because the braces are subjected only to tension stresses, they may be made of small diameter wire, rod, cable, chain, or the like of far lighter weight than braces subjected to compression loads.

While the invention has been described herein with respect to a specific embodiment of the invention, it will be obvious to those skilled in the art that various changes may be made therein without departing from the invention as defined in the appended claims. For example, it will be apparent that the manner in which the braces are hooked over the upper edge of the mast to resist dislodgment by tension forces on the braces is capable of considerable variation to accomplish essentially the results described above to varying degrees.

What is claimed is:

l. A boom structure adapted to be mounted horizontally on a vertically disposed hollow mast for supporting an array of antenna elements or the like, comprising an elongated boom, a bracket secured to said boom between its ends for gripping the mast at a selected elevation below the upper end thereof, and a pair of tension braces in the form of substantially straight resiliently flexible rods adapted to extend diagonally in an upwardly converging direction to the top of the mast from points spaced outwardly along the boom on opposite sides of said bracket, each of said tension brace rods having one end pivotally secured to said boom at one of said points for pivoting in a vertical plane generally parallel to the boom and having a hook structure at its opposite end, said hook structure of each tension brace rod comprising a leg, extending at an acute angle to the rod in said vertical plane to project downwardly into the open upper end of said mast and transversely extending means on said leg for engaging the inside surface of the mast on diametrically opposite sides thereof to hold said leg against substantial transverse movement inside the mast due to variations in the loading of said tension braces, said leg being of small cross-sectional dimensions relative to the transverse dimension of said means.

2. A boom structure adapted to be mounted horizontally on a vertically disposed hollow mast for supporting an array of antenna elements or the like, comprising an elongated boom, a bracket secured to said boom between its ends for gripping the mast at a selected elevation below the upper end thereof, and a pair of tension braces in the form of substantially straight resiliently flexible rods adapted to extend diagonally in an upwardly converging direction to the top of the mast from points spaced outwardly along the boom on opposite sides of said bracket, each of said tension brace rods having one end pivotally secured to said boom at one of said points for pivoting in a vertical plane generally parallel to the boom, and each of said tension brace rods having its opposite end bent in said plane of pivotal movement to provide an angularly disposed leg for projecting downwardly into the open upper end of said mast and having a terminal portion bent to extend generally transversely of the leg as a lateral projection thereon to hold the lower end of the leg against substantial horizontal movement in said plane within said mast, the cross-sectional dimensions of said leg being small relative to the transverse length of said laterally projecting terminal portion of the angularly disposed leg.

3. A boom structure according to claim 1, each of said tension braces, at least between its point of pivotal attachment to said boom and the opposite bent end portion thereof, being a thin resiliently flexible rod, whereby the braces may be resiliently bent over transverse antenna elements carried by the boom to facilitate packaging the boom, with the tension braces and antenna elements attached, in a carton of minimum dimensions.

4. A boom structure according to claim 1, said opposite bent end of each of said tension braces being made of thin resiliently flexible rod, and a terminal portion of said opposite bent end of each of said tension braces making an angle of substantially less than 90 with said downwardly projecting portion thereof, so as to project transversely and upwardly therefrom to a free end for resiliently engaging the inside surface of the mast on one side thereof while said downwardly projecting portion lies along the inside surface of the mast at the opposite side thereof.

References Cited in the file of this patent UNITED STATES PATENTS 845,248 Morgan Feb. 26, 1907 1,166,212 Hoos Dec. 28, 1915 1,416,586 Stalder May 16, 1922 1,648,462 Neville Nov. 8, 1927 2,208,196 Pitt July 16, 1940 

